PoNTE will focus its activities on the investigation of genetics, biology, epidemiology, vector ecology and economic impacts of three main pathosystems that threaten strategic crops and natural landscapes in the EU:
- Xylella fastidiosa (Xf) and hemipteran vector species. The harmful bacterium Xf is involved in a new and severe olive disease (Olive Quick Decline Syndrome – OQDS) firstly reported in 2013 in southern Italy (Apulia region, Salento peninsula). Preliminary investigations showed that symptomatic olive trees were affected by a biocomplex of pests and plant pathogens: the Gram-negative bacterium Xf, several pathogenic fungal species and Zeuzera pyrina (Leopard moth). Xf was previously isolated from olive in California, whose strain proved to be phylogenetically related to subsp. multiplex, and classified as “Genotype A”. In contrast, Xf isolated from OQDS in Italy was identified as a novel and distinct genotype (denoted as “CoDiRO Xf strain”), which has a phylogenetic relationship with isolates of Xf subsp. pauca. In February 2014, a Xf strain with a genetic profile similar to the CoDiRO Xf was found and identified in oleander in Costa Rica. Although Xf is widely distributed and studied in the Americas due to diseases caused in grapevine, fruit trees, and landscape plants, the recent outbreak of Xf in olive trees in southern Italy, is the first confirmed presence of Xf in the EU. Xf is exclusively transmitted by xylem-fluid feeding insects. A preliminary survey of the hemipteran population in Xf foci area indicated that the primary xylem-feeding insect there was the spittlebug Philaenus spumarius. PCR assays of head capsules of P. spumarius collected from weeds in olive groves with OQDS in this area showed a high percent was positive for Xf and transmission tests proved P. spumarius main role in the Xf CoDiRO strain transmission.
- ‘Candidatus Liberibacter solanacearum’ and psyllid vector species. CaLsol is a recently described phloem-limited, Gram-negative, not culturable bacterium that has emerged as one of the most important pathogens affecting potato and other solanaceous crops (i.e. tomato and pepper) in the Americas and New Zealand. Recently EPPO has recommended member countries to regulate solanaceous haplotypes of CaLsol and its psyllid vector Bactericera cockerelli as quarantine pests, since non-solanaceous CaLsol haplotypes have now been found in Europe associated with diseased carrots and celery. The emergence of these CaLsol haplotypes in carrots and celery has raised serious concerns about the risk that they pose to potato and other solanaceous crops across the whole EU.
- Hymenoscyphus fraxineus (anamorph. Chalara fraxinea) and new and exotic Phytophthora species. Hp is a pathogen introduced, for the first time in Poland in 2006, via plant trade, mainly affecting common ash (Fraxinus excelsior) and the narrow-leafed ash (F. angustifolia). The disease is usually fatal and has now been reported in most continental European countries as a very serious threat to ash populations. In addition, an increasing number of new emerging diseases affecting forest trees caused by several Phytophthora spp. is leading to significant economic losses and pose considerable risks to natural ecosystems. The knowledge of the genus Phytophthora is still limited and some hybrid species are still evolving, potentially increasing the risk of colonization of new forest hosts.